<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>定时器</title>
</head>
<body>
    <INPUT TYPE="button" VALUE=" 计时开始" id="dv">
    <script type="text/javascript" src="jquery-1.8.3.min.js"></script>
    <script type="text/javascript">
        $('#dv').click(function(){

            setTimeout("alert('三秒到了')",3000);
        })
            
           

    </script>


   
</body>
</html>